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virtio-net: fix page miscount during XDP linearizing 

We don't put page during linearizing, the would cause leaking when
xmit through XDP_TX or the packet exceeds PAGE_SIZE. Fix them by
put page accordingly. Also decrease the number of buffers during
linearizing to make sure caller can free buffers correctly when packet
exceeds PAGE_SIZE. With this patch, we won't get OOM after linearize
huge number of packets.

Cc: John Fastabend <john.r.fastabend@intel.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Acked-by: John Fastabend <john.r.fastabend@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jason Wang 2016-12-23 22:37:26 +08:00 committed by David S. Miller
parent 275be061b3
commit 56a86f84b8
1 changed files with 12 additions and 9 deletions
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21
drivers/net/virtio_net.c
View File

@ -483,7 +483,7 @@ xdp_xmit:
* anymore.
*/
static struct page *xdp_linearize_page(struct receive_queue *rq,
u16 num_buf,
u16 *num_buf,
struct page *p,
int offset,
unsigned int *len)
@ -497,7 +497,7 @@ static struct page *xdp_linearize_page(struct receive_queue *rq,
memcpy(page_address(page) + page_off, page_address(p) + offset, *len);
page_off += *len;
while (--num_buf) {
while (--*num_buf) {
unsigned int buflen;
unsigned long ctx;
void *buf;
@ -507,19 +507,22 @@ static struct page *xdp_linearize_page(struct receive_queue *rq,
if (unlikely(!ctx))
goto err_buf;
/* guard against a misconfigured or uncooperative backend that
* is sending packet larger than the MTU.
*/
if ((page_off + buflen) > PAGE_SIZE)
goto err_buf;
buf = mergeable_ctx_to_buf_address(ctx);
p = virt_to_head_page(buf);
off = buf - page_address(p);
/* guard against a misconfigured or uncooperative backend that
* is sending packet larger than the MTU.
*/
if ((page_off + buflen) > PAGE_SIZE) {
put_page(p);
goto err_buf;
}
memcpy(page_address(page) + page_off,
page_address(p) + off, buflen);
page_off += buflen;
put_page(p);
}
*len = page_off;
@ -555,7 +558,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
/* This happens when rx buffer size is underestimated */
if (unlikely(num_buf > 1)) {
/* linearize data for XDP */
xdp_page = xdp_linearize_page(rq, num_buf,
xdp_page = xdp_linearize_page(rq, &num_buf,
page, offset, &len);
if (!xdp_page)
goto err_xdp;